Nancy unit test doesn't work when requesting static content

I have a Nancy based web project and a unit test project using MSTest referencing the web project.

I have added a robots.txt file to the Content folder in the web project. I added a static content path to it using nancyConventions.StaticContentsConventions.AddFile("/robots.txt", "/Content/robots.txt"); in the ConfigureConventions method in Bootstrapper.

The unit test looks like this:

[TestMethod]
public void Get_Robotstxt_Should_Return_Status_OK()
{
    // Given
    var browser = new Browser(new Bootstrapper());

    // When
    var result = browser.Get("/robots.txt");

    // Then
    Assert.AreEqual(HttpStatusCode.OK, result.StatusCode);
}

The code actually works fine when deployed, it is just the test that doesn't work.